From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 48A34C433EF for ; Mon, 25 Jul 2022 16:52:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231622AbiGYQwX (ORCPT ); Mon, 25 Jul 2022 12:52:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47726 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234845AbiGYQwW (ORCPT ); Mon, 25 Jul 2022 12:52:22 -0400 Received: from mail-qv1-xf33.google.com (mail-qv1-xf33.google.com [IPv6:2607:f8b0:4864:20::f33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6E2411D0CD for ; Mon, 25 Jul 2022 09:52:19 -0700 (PDT) Received: by mail-qv1-xf33.google.com with SMTP id t7so8837861qvz.6 for ; Mon, 25 Jul 2022 09:52:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20210112.gappssmtp.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=j0BaZSzqD5eIgwyip/HS4aDnwW9Jp806htc77k2W+9I=; b=YrRC8+DcvcJ+j3/daDEZUkXI7wwrYxc1PEjLb5WJCKV4hOP1uHTC/ifMwxGxMiDkfx /A82VqK1LTw9pVhvRXWQeyXrrPJ2ZvCuG5iWP7cY8NmWkKUfWofwwTglQWitP4sLRpre NB5VpzmQIT0yR8C+q/8SpRe6N4qEXuOmhz9/zyJDdIRw6IQfETk2K2RZNRdauaalnISk ecXU6u6eJyO8O/HQW59YX4MJEK3q8L7+iGwgT+B0Xfmvz2s9vSCXiUlMoZjDizM7CmZj Pva3rt58bJXcA2sOVprKVekCrokJioAdbUfKQmHTFPMiKttfucAsODDHed2z6c5VspUe 9oNA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=j0BaZSzqD5eIgwyip/HS4aDnwW9Jp806htc77k2W+9I=; b=7Npyv6YzDvEVhI8seCVW1BwX68LDmH0wQ4tAx5va9o+zyRn9nSkGBp2P6SwrxqX8Kb EJvu+8qnsXfHfq2uLdjDsVnQH5b4cNP6AHiPNIy+n5eOtps9tlX/Esx1KmEEavRhWUBu lp4j/A3X2JNLQdVajClBTEqozawqwHnu0YB8HR+hbU2XGP4t7bM82YEKYydVcxvqieyV Sa1XvSmBiIlIBQoFAbPvxI0afSkQGpjbQumpr1bHypZds6clbYQz4K+qAyzlXojAKfxN d4/MYaFhNZyjaKss+KbvKtU5D+b8sIq12RcYfoiRNTWzieKiOexon69s2d5Se/NkKlSi CMHg== X-Gm-Message-State: AJIora8sXCQkozhXhfRE172E98yx1yNUV/Ogsig40hE+HXJGnbWBnZSq +Z2V6OeqPD2w6d3i1d+yoYdn/g== X-Google-Smtp-Source: AGRyM1uv3LFH6aM79vzCkplcfzTZ3m25YJ7ns1XG6o8aG/GGTPTrtN6PwrSDI9Hn7ptl4H/XTiIloQ== X-Received: by 2002:ad4:5de4:0:b0:474:2384:a0e9 with SMTP id jn4-20020ad45de4000000b004742384a0e9mr11516834qvb.79.1658767938522; Mon, 25 Jul 2022 09:52:18 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::1:994f]) by smtp.gmail.com with ESMTPSA id u20-20020ac858d4000000b00304f3e320f2sm7915678qta.4.2022.07.25.09.52.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Jul 2022 09:52:18 -0700 (PDT) Date: Mon, 25 Jul 2022 12:52:17 -0400 From: Johannes Weiner To: Chengming Zhou Cc: surenb@google.com, mingo@redhat.com, peterz@infradead.org, tj@kernel.org, corbet@lwn.net, akpm@linux-foundation.org, rdunlap@infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, songmuchun@bytedance.com, cgroups@vger.kernel.org Subject: Re: [PATCH 8/9] sched/psi: add kernel cmdline parameter psi_inner_cgroup Message-ID: References: <20220721040439.2651-1-zhouchengming@bytedance.com> <20220721040439.2651-9-zhouchengming@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220721040439.2651-9-zhouchengming@bytedance.com> Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Thu, Jul 21, 2022 at 12:04:38PM +0800, Chengming Zhou wrote: > PSI accounts stalls for each cgroup separately and aggregates it > at each level of the hierarchy. This may case non-negligible overhead > for some workloads when under deep level of the hierarchy. > > commit 3958e2d0c34e ("cgroup: make per-cgroup pressure stall tracking configurable") > make PSI to skip per-cgroup stall accounting, only account system-wide > to avoid this each level overhead. > > For our use case, we also want leaf cgroup PSI accounted for userspace > adjustment on that cgroup, apart from only system-wide management. I hear the overhead argument. But skipping accounting in intermediate levels is a bit odd and unprecedented in the cgroup interface. Once we do this, it's conceivable people would like to do the same thing for other stats and accounting, like for instance memory.stat. Tejun, what are your thoughts on this?